I need help on a carb. issue bad, please help !! here is the senario, I have an 88 vmax, Ii have never seen carburetors do this before, the float seems to be getting stuck in the carbs with in an hour of riding it , virtually every time. I have completely cleaned out the carbs, used sea foam and even replaced the float needles today, The bike ran the best it ever did for about 1/2 hour then boom out of no where 1 carb starts over flowing out of the float vent choking out that cylinder ! The only way to stop it is to shut off the bike drain that bowl, and resart it ! then its good for about another 1/2 hour, and here is the ridiculous part, another different one will do the same !! not always the same carb?!?!?!?!? repeat the above and all is good again, I have changed the fuel filer twice, the tank seems clean, it has been creamed a few years ago, I have checked the floats to the best of my knowledge, and none seem to be sticking or sinking, the needle springs are all on the floats where they should be, and the float setting is done according to the dry setting forum topic. then synced perfect at 800-1000 rpms - I think I have done everything by the book? I dont know what else to do -- please someone have an idea? The season is running out !!!!:bang head::bang head::bang head::bang head::bang head::bang head::bang head::bang head::bang head::bang head::bang head::ummm::ummm::ummm::ummm::ummm:
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Shuriken
Well-Known Member
You can remove the float and stick it in a bowl of warm water and see if it has any holes in it. If the float fills up with fuel or emits little air bubbles, that would be a problem.
When it floods, does it keep flooding or does it eventually stop?
Remove the carbs, check and clean them again. Make sure your float level is not too high (rich). See this thread:
http://www.vmaxforum.net/showthread.php?t=1427&highlight=float+height
Before you put the float bowl back on, turn the carb upside down from its normal orientation so that gravity is holding the weight of the float against the needle valve assembly (to close it). Gravity is enough to close the valve. Blow into the fuel inlet pipe and see if you can hear air escaping from the needle valve assembly. If you can, it's not sealing.
If it's only flooding out of that carb, I don't expect that your tank/filter/lines are rusted or crapped up with Kreem or it would affect the other carbs as well. It has to be in that carb only. I would also make sure you have the float tang properly fitted to the needle assembly.
Also, check to make sure the rubber plugs on the jet block are in good shape and that the main jet is fully screwed tight and seated well.
When it floods, does it keep flooding or does it eventually stop?
Remove the carbs, check and clean them again. Make sure your float level is not too high (rich). See this thread:
http://www.vmaxforum.net/showthread.php?t=1427&highlight=float+height
Before you put the float bowl back on, turn the carb upside down from its normal orientation so that gravity is holding the weight of the float against the needle valve assembly (to close it). Gravity is enough to close the valve. Blow into the fuel inlet pipe and see if you can hear air escaping from the needle valve assembly. If you can, it's not sealing.
If it's only flooding out of that carb, I don't expect that your tank/filter/lines are rusted or crapped up with Kreem or it would affect the other carbs as well. It has to be in that carb only. I would also make sure you have the float tang properly fitted to the needle assembly.
Also, check to make sure the rubber plugs on the jet block are in good shape and that the main jet is fully screwed tight and seated well.
richwrench
Well-Known Member
If the problem changes from carb to carb, I would suspect fuel press. might be getting too high. Do you have a fuel press. gauge you can monitor while you ride ?
Thanks for the replies guys, as for a fuel pressure gauge that i can monitor, i do not have one, and its so tight , i dont even know how to make that happen, there is just no room on this bike, but if it was a fuel pressure problem wouldnt it affect all the carbs?? as for the first post, i have done all the above except putting the floats in a bowl of water, i assume they are not hollow floats but full foam, so I didnt think they could be sinking,they look immacualte, but if i had a bad float why would this problem seem to jump from carb to carb, and then when I drain off the bowl, go back to working good again? also as for the cream in the tank, does that degrade over time? and if it does wont the filer catch any debris? i have checked the rubber plugs in the metering block and all are good with no cracks and relitively tight, and the floats are set right. This problem is going to make me sell this thing, does anyone have a set of carbs they want to sell cheap????:bang head::bang head: more ideas please help !!!
Shuriken
Well-Known Member
Guess I didn't catch the first time that you said it is happening on different carbs.....
When you drain the bowl, does anything come out besides fuel? Yes, Kreem can break down over time. I personally think Kreem sucks and that epoxy is the best way, (see: http://www.caswellplating.com/aids/epoxygas.htm ) but that may be beside the point.
What if there is some crud in the fuel inlet pipes... If it clogs up one carb's feed tube, all of the fuel and pressure forces too much fuel to another carb? Then you drain a bowl, which relieves pressure and the crud loosens? I don't think it's a fuel filter problem but a clear plastic filter will show you if anything is being caught.
You're sure the float tangs are properly fitted to the fuel jet needles? You're sure that your needles are sealing by turning the carbs over and blowing air into the inlet fuel pipes? I know it's a PITA to yank the carbs but the more you do it the faster it goes. First time I did the carbs on mine it took me 10 light years to reconnect the throttle linkage but now I have some tricks. Can get the carbs off in like 20 minutes. I'd say yank the carbs and while they are apart, come back with any of your observations. I don't think you'll find any cheap carbs but you may find someone who can ship you a spare set for trial....
I feel your pain... I'm still trying to dial mine in. Spent like 4 years trying to dial in my XS11 carbs.....
The floats do not feel to me like they are foam filled. The XS11 floats were air filled. I doubt Yamaha changed that from the XS11.... I've seen float problems before.
When the carb starts overflowing, can you *gently* tap around the carb to get it to stop? Don't put a hole in your float bowl by tapping too hard but if you can tap and get it to stop flowing, you definitely have a needle/seat issue. How are the seats - are they scratched or scored?
Just because it seems to happen to another carb doesn't mean there is no pattern in the problem. If you find that it always starts with one carb and ends up with another and repeats, that would help with the troubleshooting.
If - when it isn't flooding - the bike runs really well, I wouldn't sell it because of a carb problem..... You won't be able to get as much because of the unsolved problem.
If you get stuck on the carbs you could send them here:
http://www.motorcyclecarbs.com/Services_W123.cfm
Start simple. Make sure everything is at stock, especially float level. One trick is to attach a clear tube to each bowl drain... you can do this with a special screw...... then you hold the tube higher than the bowl and watch the fuel level rise up the tube. You compare the levels of the tubes. If they are borderline too high when the engine is cold, they may flood when it warms up. You may have 2 carbs with rich float levels. Or 2 carbs with bad floats. Gotta be a pattern here we can follow....
Does the fuel pump operate too much? Should click when the bike starts but shouldn't be going nuts. You can disconnect the carb fuel inlet pipe and then turn on the key to observe how much fuel the pump is squirting.
When you drain the bowl, does anything come out besides fuel? Yes, Kreem can break down over time. I personally think Kreem sucks and that epoxy is the best way, (see: http://www.caswellplating.com/aids/epoxygas.htm ) but that may be beside the point.
What if there is some crud in the fuel inlet pipes... If it clogs up one carb's feed tube, all of the fuel and pressure forces too much fuel to another carb? Then you drain a bowl, which relieves pressure and the crud loosens? I don't think it's a fuel filter problem but a clear plastic filter will show you if anything is being caught.
You're sure the float tangs are properly fitted to the fuel jet needles? You're sure that your needles are sealing by turning the carbs over and blowing air into the inlet fuel pipes? I know it's a PITA to yank the carbs but the more you do it the faster it goes. First time I did the carbs on mine it took me 10 light years to reconnect the throttle linkage but now I have some tricks. Can get the carbs off in like 20 minutes. I'd say yank the carbs and while they are apart, come back with any of your observations. I don't think you'll find any cheap carbs but you may find someone who can ship you a spare set for trial....
I feel your pain... I'm still trying to dial mine in. Spent like 4 years trying to dial in my XS11 carbs.....
The floats do not feel to me like they are foam filled. The XS11 floats were air filled. I doubt Yamaha changed that from the XS11.... I've seen float problems before.
When the carb starts overflowing, can you *gently* tap around the carb to get it to stop? Don't put a hole in your float bowl by tapping too hard but if you can tap and get it to stop flowing, you definitely have a needle/seat issue. How are the seats - are they scratched or scored?
Just because it seems to happen to another carb doesn't mean there is no pattern in the problem. If you find that it always starts with one carb and ends up with another and repeats, that would help with the troubleshooting.
If - when it isn't flooding - the bike runs really well, I wouldn't sell it because of a carb problem..... You won't be able to get as much because of the unsolved problem.
If you get stuck on the carbs you could send them here:
http://www.motorcyclecarbs.com/Services_W123.cfm
Start simple. Make sure everything is at stock, especially float level. One trick is to attach a clear tube to each bowl drain... you can do this with a special screw...... then you hold the tube higher than the bowl and watch the fuel level rise up the tube. You compare the levels of the tubes. If they are borderline too high when the engine is cold, they may flood when it warms up. You may have 2 carbs with rich float levels. Or 2 carbs with bad floats. Gotta be a pattern here we can follow....
Does the fuel pump operate too much? Should click when the bike starts but shouldn't be going nuts. You can disconnect the carb fuel inlet pipe and then turn on the key to observe how much fuel the pump is squirting.
MONTREALMAX
Well-Known Member
Any idea how much fuel the pump should be pumping?
WELL I CHECKED THE FUEL PRESSURE AND IT SEEMS NORMAL, THE PUMP TURNS OFF WHEN IT BUILDS PRESSURE AND THE OCCASIONAL CLICKS WHEN MORE IS REQUIRED -- I HAVE NOTCED THIS PROBLEM SEEMS TO REALLY START AFTER I HAVE BEEN CRUISING IT AROUND OR UNDER 3500 RPM FOR PROLONGED TIME, AND IS FULLY WARMED UP. I RODE IT LAST NIGHT, AND AFTER ABOUT 1/2 HOUR I STOPED AT A LIGHT AND BLAM !!! THERE IT WAS , SO I RAN UP THE RPMS AND HIT A FEW BUMPS IN THE ROAD , KICKED VBOOST A FEW TIMES AND IT WENT BACK TO FINE TILL I GOT HOMW, SEEMS IF I CAN RUN THE EXCESS FUEL OUT OF THE BOWL IT RESETS IT SELF? WHAT ABOUT THAT DIAPHRAM UNDER THE SMALL SIDE COVER? COULD THAT HAVE SOMETHING TO DO WITH LETTING EXCESS FUEL IN THE BOWL ON DECLERATION??? SORRY FOR THE CAPS LOCK, MY WORK COMPUTER ONLY TYPES CAPS !! IM NOT YELLING:bang head::bang head:
Shuriken
Well-Known Member
Since it consistently happens, it doesn't sound like occasional crud in the fuel inlets. You checked the fuel pump and described what should be normal operation there as well.
Under 3500 performance is affected a lot by float height, pilot jets, idle mix settings, etc. You said it seems to get worse when fully warm. You also said it clears up when you wind up the bike and hit boost. Just all sounds to me like float height issues or float problems. My money is on float height or float problems.
Have you seen eBay item: 370079712687 ?
Under 3500 performance is affected a lot by float height, pilot jets, idle mix settings, etc. You said it seems to get worse when fully warm. You also said it clears up when you wind up the bike and hit boost. Just all sounds to me like float height issues or float problems. My money is on float height or float problems.
Have you seen eBay item: 370079712687 ?
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